Metal cleaning device



July 21, 1970 D, NALLEY ETAL 3,521,407

METAL CLEANING DEVICE Filed June 13, 1967 3 Sheets-Sheet 1 July 21,1970

Filed Jfine 13. 1967 n. B. NALLEY T METAL CLEANING DEVICE 3 Sheets-Sheet2 July 21, 1970 D. a. NALLEY ET AL METAL CLEANING DEVICE I 5Sheets-Sheet 3 Filed June 13. 1967 United States Patent l 3,521,407METAL CLEANING DEVICE Don B. Nalley and Davis L. Baughman, Hagerstown,Md., assignors to The Carborundum Company, Niagara Falls, N.Y., acorporation of Delaware Filed June 13, 1967, Ser. No. 645,812 Int. Cl.B24c 7/00 U.S. C]. 51-12 Claims ABSTRACT OF THE DISCLOSURE The metalcleaning device operates under the direct pressure system for airblasting or shot peening wherein the treating media is fed to thetreating nozzle by a feed chamber. Air flows through the nozzle to applythe media against the part treated. A supply chamber communicates withthe feed chamber and a metering chamber communicates with the supplychamber. The pressure source for the treating nozzle also maintains thefeed chamber under constant pressure and intermittently pressurizes thesupply chamber. An independent source is utilized for controlling valvesbetween the various chambers.

BACKGROUND OF THE INVENTION There is a rapidly expanding use of shotpeening of for example aerospace structural components to prevent stresscorrosion and to improve service life by reduction of fatigue failures.It has been further more desirable to peen with direct pressurev systemsrather than the suction feed and gravity flow type peening methodsbecause of the higher shot velocities possible with direct pressuresystems. For peening, direct pressure systems require constant airpressure on the shot being fed into the high velocity air stream. Theability :of a system to automatically reload the pressurized shotfeeding chamber without air pressure fluctuation and shot flowinterruption is seldom if ever obtained in practice.

Present direct pressure air blasting and peening systems utilize twoabrasive or shot chambers, one disposed over the other. The top chamberincorporates a feeder valve and its upper portion to permit the abrasiveor shot to enter. This chamber is not pressurized when receiving a newabrasive or shot charge, but rather is intermittently pressurized whendumping into the constantly pressurized bottom chamber. The refilledcycle is operated by a timer set to a suitable time cycle to prevent thelower chamber from running out of abrasive or shot. These systems,however, have the following disadvantages: (1) the abrasive wears thesealing element of the filling valves; (2) a blasting pressure drop andshot flow interruption occurs during the refilling cycle; (3) there isconstant air leakage past the filler valve seals when they close onabrasive or shot; and (4) the operation is restricted to a relativelynarrower pressure range such as 40-80 p.s.i.

BRIEF SUMMARY OF THE INVENTION An object of this invention is to providea metal treating system which eliminates the above disadvantages.

A further object is to provide such a system which includes a valvearrangement that will not close on abrasive or shot and will, therefore,be inherently non-leak- A still further object is to provide such asystem wherein there is no abrasive or shot flow variations caused byair pressure fluctuations during the abrasive or shot reloadingoperation.

Astill further object is to provide such a system which operates equallywell over large air pressure ranges.

In accordance with this invention the system includes threecommunicating chambers which may be designated 3,521,407 Patented July21, 1970 as a metering chamber communicating with a supply chamber whichin turn communicates with the feed chamber for supplying a treatingmedia such as abrasive or shot to a nozzle. A pressure sourcepressurizes both the feed and supply chambers as well as the nozzleWhile a separate pressure solurce controls the valves between thechambers. Advantageously the metering chamber may be of less capacitythan the supply chamber to prevent an overflow ofthe supply chamberwhich would result in the valve seating upon the abrasive or shot.

In accordance with another aspect of this invention the chambers areconstructed in such a manner as to be selfcleaning; and acompartmentalized feed h'opper communicates with the metering chamber soas to selectively supply diiferent types of treating media.

[In an advantageous form of this invention the first pressure sourcemaintains the feed chamber under constant pressure and maintains thesupply chamber under an intermittent pressure by the inclusion of anexhaust valve. The various valves between the chambers and the exhaustvalve are sequentially controlled to insure proper operation of thedevice. The actuation of this sequential control may be effected by aconventional level indicating switch which detects when the cleaningmedia has fallen to a predetermined level in the feed chamber.Sequential valve control is such that abrasive is admitted into themetering chamber at the same time the supply chamber is emptying intothe feed chamber. This insures that the total amount of abrasive mediapresent in any or all of the three chambers can be accommodated at alevel below the filler valve in the feed chamber to guarantee thatduring start up of the system following an inadvertent failure of thepneumatic or electrical controls, the valves will not close on abrasive.

The valves utilized in the device are in and of themselves worthy ofspecial note. Each of the valves between the various chambers includes apneumatic cylinder piston rod assembly having a ball mounted on the endof the piston rod. A conical skirt is loosely seated on the ball forswivel type movement. The movement of the conical skirt may be limitedand controlled by a flange on the piston rod with internal projectionson the skirt disposed in the path of motion of the flange.

IN THE DRAWINGS FIG. 1 is a schematic view of one embodiment of thisinvention;

FIG. 2 is a cross-sectional view in elevation of a portion of theembodiment shown in FIG. 1;

FIG. 3 is an enlarged view of the valve arrangement shown in FIG. 2;

FIG. 4 is a cross-sectional view taken through FIG. 2 along the line 44;and

FIG; 5 is a schematic view of the pneumatic arrangement of the deviceshown in FIGS. 1-4.

DETAILED DESCRIPTION As indicated in FIG. 1 the apparatus 10 includesfor example a direct pressure nozzle 12 which communicates with feedchamber 14. Disposed above feed chamber 14 is supply chamber 16 which inturn communicates with metering chamber 18 while feed hopper 20 suppliesthe treating media such as abrasive or shot to the metering chamber 18.Metering chamber 18 is of such a size as shown for example in FIG. 2that its full capacity is less than that of either chambers 16 or 14.Thus when a full charge of abrasive or shot drops into a lower chamberit will completely pass through valve 22 or valve 24 preventing thesevalves from sealing on abrasives or shot.

In operation metering chamber 18 is never pressurized While chamber 14is constantly pressurized and chamber 16 is intermittently pressurized.The pressurization of chambers 14 and 16 is controlled by pressuresource 26 which also provides the air pressure for nozzle 12 while thevalves 22 and 24, as well as valve 28 are controlled by pressure source30.

Mounted at a predetermined level in chamber 14 is a level indicatingswitch 32 such as commercially available devices. The operation of theswitch is generally as follows: When the level of treating media 34(FIG. 2) is below a predetermined level, the switch is actuated. Thusproximity or level indicating switch 32 senses when the level ofabrasive or shot is low and signals for a new charge. At this stage ofthe operation supply chamber 16 has an abrasive or shot charge as" shownin FIG. 2. When proximity switch 32 signals for abrasive or short, atimer (not shown) connected thereto starts to set in motion thefollowing events: Valve 38 (FIG. 1) is sequenced to pressurize chamber16 to the constant pressure of feed chamber 14. Valves 22, 24 and 28 areclosed. Valve 24 then opens and abrasive or shot in chamber 16 dropsinto chamber 14. Valve 24 then closes. Valve 38 closes venting chamber16 to the atmosphere through port 42. Simultaneously with valve 24opening valve 28 also opens filling chamber 18 after which valve 28closes. Valve 22 then opens dropping the abrasive or shot into chamber16. Valve 22 then closes. This completes one reload cycle and the systemis ready to reload chamber 14 at the next signal from proximity switch32.

Advantageously the valves 22 and 24 which admit the abrasive or shot andwhich close for the air pressurization of the chambers, do not close andseal on abrasive particles and shot because the top and metering chamber18 is smaller than chambers 14 and 16. Similarly as clearly shown inFIG. 1 and more particularly in FIG. 2 feed chamber 14 is of greatercapacity than supply chamber 16. As later described valves 22, 24 arepositively powered by air cylinder or other suitable devices from anexternal air supply 30 instead of using the chamber pressurized airsupply 26.

The device of this invention has the following advantages over the priorart: 1) the reload cycle is quick permitting large abrasive or shotflows through a relatively small unit; (2) the blasting air pressure canbe varied over a wide range such as for example 3-90 p.s.i.; (3) thereis no blasting pressure variation during the valve cycling to therebyassure a continuous blasting or peening action; (4) valve wear and airleakage through the valves is minimized since the valves do not close onthe abrasive or shot; the unit is designed to be internallyself-cleaning so that as later described complete changes in abrasive orshot size can be made completely and quickly; (6) valve 28 is a normallyclosed spring loaded valve which will shut off abrasive or shot flowautomatically in the event of power or control air failure to therebyprevent the inadvertent filling of the entire system with shot orabrasive.

As indicated above the various chambers are so designed as to beinternally self-cleaning. For example the bottom of each chamber istapered whereupon the opening of a valve permits the abrasive or shot toautomatically flow downwardly out of the chamber. In conjunction withthis self-cleaning ability feed hopper is made compartmentalized asschematically shown, for example in FIG. 1. Thus different types of shotor abrasive can be stored in feed hopper 20. Each compartment includes,for example a control valve 44 to assure that only one com partment at atime communicates with metering chamber 18. Valves 44 may be anysuitable conventional manual valves or may be automatically controlledfrom a remote control panel. Thus when it is desired to change the typeof abrasive or shot used in an operation, the chambers are emptied bytheir internal self-cleaning ability and the new abrasive is alreadydisposed for feeding into the chambers.

FIG. 5 shows the pneumatic system for operating device 10. Since theoperation of this system is readily apparent from an inspection of FIG.5, it suflices to say that a single air source 46 supplies the airthrough valve 48 and filter 50 to the separate pressure sources 26, 30.Chamber 14 is mounted under constant pressure through line 52 whilechamber 16 is intermittently pressurized through line 54 which includesexhaust valve 38. The pressure source 30 in turn controls valves 24, 22,and 28 as indicated in FIG. 5.

FIGS. 2-4 show the details of valves 22 and 24. As indicated thereinvalves 22 and 24 include a cylinder 56 which is mounted on a spider 58and has a pneumatically controlled piston rod 60. At the end of pistonrod 60 is a ball 64 upon which is loosely seated a conical skirt 66. Aflange or washer 68 is also mounted on rod 60 with an internal skirtshoulder 70 and limit ring 72 positioned on each side of flange 68. Bythis arrangement it is possible for the valve element or skirt 66 tohave a swivel type movement so as to accommodate itself to possibleaxial misalignment. Additionally the provision of flange 68, shoulder 70and ring 72 serves to not only limit the amount of movement of skirt 66but also to cause skirt 66 to move toward and away from sealing ring 74in accordance with the movement of rod 60. The conically shaped skirt 66not only maximizes its universal type seating ability but also serves tothrow the falling shot or abrasive away from the piston cylinderassembly. Additionally the valve cone swivel joint takes the side forcesoff piston rod 60.

Obviously many modifications and variations of this invention arepossible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. A metal cleaning device comprising a treating nozzle, first pressuremeans connected to said treating nozzle, a treating media feed chambercommunicating with said nozzle, a supply chamber communicating with saidfeed chamber, a metering chamber communicating with said supply chamber,said first pressure means being connected for pressurizing said feed andsaid supply chambers, valve means between said feed and supply chambersand between said supply and metering chambers, second pressure means forcontrolling the actuation of said valve means, said metering chamberbeing of less capacity than said supply chamber, said chambers includingself-cleaning means, a feed hopper communicating with said meteringchamber, and said hopper being compartmentalized to store differenttypes of segregated treating media.

2. A metal cleaning device comprising a treating nozzle, first pressuremeans connected to said treating, nozzle, a treating media feed chambercommunicating with said nozzle, a supply chamber communicating with saidfeed chamber, a metering chamber communicating with said supply chamber,a feed hopper communicating with said metering chamber, said supplychamber being of greater capacity than said metering chamber, said feedchamber being of greater capacity than said supply chamber, said firstpressure means being connected for maintaining said feed chamber underconstant pressure and said supply chamber under intermittent pressure,valve means between said feed and said supply chambers and between saidsupply and said metering chamber and between said metering chamber andsaid feed hopper, and second pressure means for controlling theactuating of said valve means.

3. A device as set forth in claim 2 wherein a feed hopper communicateswith said metering chamber, said valve means also being between saidfeed hopper and said metering chamber, and means for sequentiallycontrolling the operation of'said valve means.

4. A metal cleaning device comprising a treating nozzle, first pressuremeans connected to said treating nozzle, a treating media feed chambercommunicating with said 5 nozzle, a supply chamber communicating withsaid feed chamber, a metering chamber communicating with said supplychamber, said first pressure means being connected for prcssurizing saidfeed and said supply chambers, valve means between said feed and supplychambers and between said supply and metering chambers, second pressuremeans for controlling the actuation of said valve means, said firstpressure means including means for maintaining said feed chamber underconstant pressure and means for maintaining said supply chamber underintermittent pressure, said means for maintaining said supply chamberunder intermittent pressure including an exhaust valve, a feed hoppercommunicating with said metering chamber, said valve means also beingbetween said feed hopper and said metering chamber. means forsequentially controlling the operation of said valve means, and levelindicating switch means being in said feed chamber for actuating saidmeans for sequentially controlling the operation of said valve means andexhaust valve.

5. A device as set forth in claim 4 wherein the valve means includes apneumatically actuatable shaft, a ball mounted on theend of said shaft,a conical skirt loosely seated on saidball, flange means on said shaft,and internal projection means on said skirt in the path of motion ofsaid flange means.

I References Cited UNITED STATES PATENTS 699,405 5/1902 Newhouse 51 122,443,148 6/1948 Rucki 51 12 2,597,434 5/1952 Bishop et al. 51 12 LESTERM. SWINGLE, Primary Examiner

